@x = (( $x1a, $x1b, $x1c), ( $x2a, $x2b, $x2c), ( $x3a, $x3b, $x3c), ... etc ... ($xna, $xnb, $xnc)); 

##</code><code>##

 
[[$x1a, $x1b, $x1c], [$x2a, $x2b, $x2c], [$x3a, $x3b, $x3c], ... etc ... [$xna, $xnb, $xnc]]